In the digital age, many forensic investigators, understandably, tend to focus their investigative efforts on gathering electronic evidence. Almost all cases ultimately leading to legal proceedings will involve the capture, analysis and presentation of electronic evidence. There are times however when the digital approach cannot help and the forensic investigator needs to consider other options in an effort to advance the investigation.
One of the other options that forensic investigators ‘occasionally’ turn to (and probably no more than occasionally) is fingerprint analysis. Many investigators and almost all members of the general population have no idea that fingerprint analysis can be and is performed by private sector fingerprint experts. One such expert is Russell Stuart. Russell spent 22 years as a sworn officer of the New South Wales Police. 12 of those years were as a member of the Forensic Services Group with a particular interest and specialisation in fingerprint analysis. Russell is a recognised fingerprint expert who has been awarded ‘expert’ status by the National Fingerprint Accreditation Board.
These days you typically will find Russell teaching Forensic Science at the Canberra Institute of Technology. Along with sharing his forensic science knowledge with up-and-coming crime scene experts in Australia, Russell also lectures on fingerprint identification to various government departments in Australia. This includes participants from overseas organisations such as the Iraqi, United Arab Emirates and South Pacific police services underpinning the science of fingerprint identification. In addition to his teaching schedule, Russell is engaged privately to provide his fingerprint expertise in a surprising number of criminal investigations and civil trials.
Over his career, Russell has been engaged to capture and examine fingerprint evidence from a vast array of cases from burglaries through to homicides and in more recent times explored the potential for detection of latent finger marks on improvised explosive device (IED) cases. In the world of financial crime, Russell has been engaged to investigate workplace bullying, sexual harassment and written threats against management. In 2014, he undertook a workplace investigation in which he was required to take and examine the fingerprints of 30 members of staff in one organisation in an attempt to match fingerprints found on threatening letters received by the company’s management.
So how does it work? Russell essentially is looking for ‘latent’ prints – the fingerprint residue made up of grease and oil from the hands of a person who has touched an object. When processing fingerprints, Mr Stuart starts with a less destructive method before moving through a range of more destructive contemporary options.
The first step is optical examination incorporating the application of forensic light sources, which can be enough in itself to view and detail the fingerprints without further enhancement. Applying a light source with filters using various polarizing effects on a surface can potentially allow for latent fingerprints to be seen clearly. If the optical examination is not possible, then physical, gaseous fumes (i.e. vaporised Superglue) and/or chemical solutions (dye stains or reagents) are used to reveal latent fingerprints. The method used depends on the type of receiving surface the fingerprint is on: porous surfaces (paper), semi porous (partly sealed paper/cardboard) or non-porous surfaces (glass/plastic). There are potentially hundreds of compounds (lipids) in just one fingerprint that are capable of supporting a latent fingerprint. A single fingerprint on porous paper can remain ‘detectable’ for decades.
In addition to fingerprints, marks left by palms and also the soles of an individual’s feet may also be used for identification as these are just as unique as those on the fingers and thumbs. Once a fingerprint has been detected, the examiner must determine whether the print is suitable for ‘individualisation’, which involves (comparing a latent print with a known control fingerprint (typically provided by an individual under controlled conditions).
Whilst many believe the role of a fingerprint expert is confined to crime scenes and criminal cases, fingerprint experts may be used in white-collar crime scenarios such as obtaining prints from letters or notes, petty cash boxes, locked/confidential files and office surfaces. This evidence may be used in conjunction with financial and technological evidence found by forensic accountants in order to identify the perpetrator and deliver an outcome.